U.S. Pat. No. 4,145,669, issued to Babcock et al on Mar. 20, 1979 shows a gaseous laser having an array of pin electrodes dispersed in rows spaced uniformly along the gas flow direction (FIG. 3 of that patent) and an improved configuration, modified by the substitution of a rod electrode for some of the downstream pin rows, (FIGS. 4, 5 and 6 of that patent).
Copending application U.S. Ser. No. 864,961, assigned to the assignee hereof and incorporated herein by reference shows similar electrode configurations and further teaches that a pin-rod electrode system produces the best discharge stability when there are two rows of pins followed by several rods.